What Does Engine Knock Sound Like in a Car?

[Yvonne]

Engine knock produces a rhythmic "tapping" sound during driving, similar to lightly striking a triangle. Below is an introduction to engine knock and its manifestations: Engine Knock: Commonly known as "knocking," simply put, engine knock refers to abnormal combustion inside the engine, resulting in metallic knocking sounds and even vibrations. Engine knock is an abnormal operating condition of the engine, generally referring to sudden, non-prolonged vibrations in the engine cylinder caused by irregular ignition. Users can clearly perceive abnormal engine sounds and vibrations, which reduce engine output power, increase temperature, raise fuel consumption, and cause some degree of damage to the engine. Manifestations of Engine Knock: It can be broadly categorized into two types: surface ignition and detonation. However, it's worth noting that pre-ignition, though not exactly knock, often serves as a cause leading to surface ignition and detonation.

[Evie]

I'm a regular at the auto repair shop and often hear customers describe the sound of engine knocking. It sounds like small hammers clicking against metal in the engine compartment, especially noticeable when accelerating uphill or during sudden acceleration, such as when overtaking or climbing steep slopes. The cause is usually fuel with too low an octane rating, leading to premature combustion and internal impacts; or excessive carbon buildup in the engine affecting combustion efficiency. This sound should not be ignored, as it can lead to excessive wear on piston rings, potential spark plug damage, or even cylinder scoring accidents, which are costly to repair. I recommend trying higher-octane fuel, such as 95 or above, as soon as the sound is heard. If there's no improvement, promptly visit a professional shop to check the ignition timing or clean carbon deposits. Regular maintenance is crucial—for example, changing the oil and cleaning the intake passages every 5,000 kilometers—to prevent such sudden issues. Safe driving starts with attention to detail; a healthy engine ensures worry-free travels.

[MacWeston]

While cruising on the highway in my new car, the engine suddenly started making a rattling noise, like someone was banging a metal pot inside the car, especially harsh when accelerating. A friend said it was knocking, caused by low-quality gasoline or carbon buildup inside the engine. Intrigued, I researched online and found that this sound indicates abnormal combustion, which can damage pistons and increase fuel consumption over time. So, I switched to 98-octane fuel and added a cleaning additive, and the noise disappeared after a few days. Since then, I've been more careful about fuel selection, only filling up at reputable gas stations; I also pay attention to engine sounds and take action at the first sign of trouble. While driving pleasure is great, maintenance is the real key to ensuring the vehicle is in optimal condition on the road.

[LaEmersyn]

I've driven sedans for half my life and heard too many knocking sounds. It's like a metal rod lightly tapping the cylinder, making a clattering noise, especially noticeable when accelerating uphill. It's often caused by insufficient octane or incorrect ignition timing. In the early years, I didn't understand and ignored it, only to end up with a costly engine overhaul that hurt my wallet. Now, with more experience, I immediately change the oil or find a repair shop to check when I hear this sound. Don't underestimate it; early intervention saves trouble and ensures safety.